A WWF study has found that the world's wildlife population has dropped by more than a half in the past four decades - a far greater drop than identified in a previous report. Human numbers, meanwhile, have doubled.
The World Wild Fund for Nature (WWF) found in its latest survey that there was a 52-percent decrease in the global head count for more than 10,000 different animal populations across Earth.
The 2014 Living Planet Report, released on Tuesday, looked at the change in population numbers for 3,038 of what it considers to be the most representative animal species.
It revealed a 39 percent fall in numbers across a representative sample of land-dwelling species from 1970 to 2010, with the same depletion in marine species. In freshwater populations, the drop was more marked - at 76 percent.
"The number of mammals, birds, reptiles, amphibians and fish across the globe is, on average, about half the size it was 40 years ago," the report said.
"Given the pace and scale of change, we can no longer exclude the possibility of reaching critical tipping points that could abruptly and irreversibly change living conditions on Earth," it added.
A previous report from the WWF looking at similar populations between 1970 and 2008 had found the level of decline overall to be far lower - at 28 percent. Improved measuring methods explained the huge difference, the group said.
Habitat pressures in tropics
The report highlighted a decline in biodiversity in both temperate and tropical regions, with the decline greater in the tropics. The most dramatic fall - of 83 percent - was in Latin America, with habitat loss blamed for much of the damage.
While biocapacity - the amount of life the Earth can support - has increased significantly, the report found this has been far outweighed by the increase in human numbers, up from 3.1 billion to 7 billion over the four decades.
"For more than 40 years, humanity's demand on nature has exceeded what our planet can replenish," said the report. "We would need the regenerative capacity of 1.5 Earths to provide the ecological services we currently use."
Kuwaitis were found to have the largest ecological footprint, followed by Qatar and the United Arab Emirates. Many poorer countries such as India, Indonesia and Republic of Congo, the WWF found, had footprints that were easily sustainable.
rc/lw (AFP, AP, Reuters)